The present invention generally relates to a cold water infusible tea leaf, to processes for obtaining such leaf and to the improved cold water infusion products thereby obtained.
Black tea is traditionally produced from fresh green tea leaves (Camellia sinensis) by a process comprising four major steps: withering, rolling, fermentation and firing. Withering is a process whereby the freshly plucked green tea leaves are stored until the moisture content is reduced to about 55-72% of the leaf weight. The withered leaves are crushed by rolling or maceration in order to break down the leaf cell structure and bring enzymes and the substrate polyphenols into contact. During fermentation the simple flavonoids in green tea leaf are oxidized by endogenous tea enzymes to produce the polyphenols that impart a bright red color and the astringent flavor to black tea. Tea fermentation is truly an enzymatic process and is not the typical fermentation used in brewing of alcoholic beverages. Two enzymes, polyphenol oxidase and peroxidase catalyze the oxidation of simple catechins to the more complex polyphenols; namely theaflavins (TF) and thearubigens (TR).
Fermented teas are fired (dried) with hot, dry air reducing the moisture content of the leaves to less than 5%. Firing of teas arrests fermentation by inactivating enzymes and results in development of color and flavor from chemical oxidation and creates the final balance of tea aroma. Following drying, the leaves are then sorted and graded to yield a commercial black tea product. The process of tea manufacture is described in great detail by Robertson 1992 (Tea: Cultivation to Consumption. Wilson, K. C. and Clifford, M. N., Eds., Chapman Hall, London)
Tea beverage is prepared from the black tea leaf manufactured by the above process by infusing the tea leaves loose or in a tea bag in hot freshly boiled water for a few minutes. After removing the tea leaf, the beverage is then consumed hot or cold as iced tea.
It is well known that the majority of the tea consumed in the U.S. is iced tea prepared by cooling down tea beverage brewed using hot freshly boiled water, by dissolving instant tea powders in water or in the form of ready-to drink teas in cans, bottles or cartons. Iced tea prepared from tea leaf with boiling water has the fresh brewed tea flavor/astringency enjoyed around the world. However, the steps of boiling water and cooling down can be time consuming, generally taking more than 30 minutes before the ice tea beverage is ready for consumption.
Convenient as cold water soluble tea powders can be, for many consumers the quality of the final beverage is not equal to that prepared from hot infused leaves. Many consumers prefer not to use instant tea powders as they perceive them to be lacking the fresh brewed tea taste and of inferior quality.
Accordingly, a leaf tea that can rapidly infuse in cold water to produce an iced tea beverage with the color and flavor of the traditionally hot brewed iced tea would offer the consumer a convenient option to both traditional leaf tea and powdered tea products. The benefit of a cold brew tea product is two folds, the convenience of not having to boil water and wait for it to cool down, and the fresh brewed tea taste.
There are numerous methods for making cold water soluble tea powders including U.S. Pat. No. 4,051,264 and U.S. Pat. No. 3,812,266. European patent specification EP 760,213 A1 (Unilever) discloses a method of enhancing color in a tea-based foodstuff. The method involves using a tannase pre-treatment (on leaf or extract) followed by treatment with exogenous peroxidase and hydrogen peroxide to generate cold-soluble color.
International patent publication WO 97/40699 (Unilever) concerns tea processing with zeolites to generate color. There are examples of adding zeolite following tannase treatment to generate cold-water soluble tea.
U.S. Pat. No. 4,639,375 discloses treating black tea with tannase, together with other cell-wall digesting enzymes, to generate cold-water soluble instant tea powders.
When conventional teas are extracted with cold water for short periods of time (less than 15 minutes), the tea beverage produced has a low concentration of extractable tea solids, a Very light color and almost no tea-like taste. Water at temperatures of about 100xc2x0 C. is usually employed to obtain a satisfactory beverage with prior art tea leaves.
It has now been discovered that by appropriate selection of tea leaves, which are, in turn, subjected to appropriate processing, a cold brew tea beverage can be obtained. It is now possible to obtain a leaf tea that rapidly infuses and remains soluble in cold water to give a beverage with good color and flavor that is as acceptable to consumers as iced tea made from a hot infused black leaf tea. Furthermore, this product can be made from infusions of tea obtained by modifying the traditional black tea manufacturing process.
The inventive product is used to prepare a beverage with good color and taste by infusion in cold water. The product is comprised of 100% tea leaves and excludes the addition of instant tea powder or the coating of tea extracts onto the tea leaves. In other embodiments, the product may employ powders, extracts or colorants. The product infuses in cold water and can be used to produce an iced tea beverage with the color and flavor comparable to iced teas prepared by hot brewing methods.
In summary, this invention encompasses a tea leaf product that rapidly brews in cold water to produce a beverage with color and flavor characteristics substantially identical to hot brewed iced tea beverages and a process of manufacturing cold infusing black tea leaf. This product and processes for its preparation will be described in detail in the xe2x80x9cDetailed Description of the Inventionxe2x80x9d.
xe2x80x9cTeaxe2x80x9d for the purposes of the present invention means leaf material from Camellia sinensis var. sinensis or Camellia sinensis var. assamica. It also includes herbal teas such as rooibos tea obtained from Aspalathus linearis, however, most herbal teas are a poor source of endogenous fermenting enzymes. xe2x80x9cTeaxe2x80x9d is also intended to include the product of blending two or more of any of these teas.
xe2x80x9cLeaf teaxe2x80x9d for the purposes of this invention means a tea product that contains leaves of one or more tea origins in an uninfused form.
xe2x80x9cCold water infusiblexe2x80x9d for the purposes of this invention means giving good color, flavor and mouthfeel in a short infusion time, i.e., less that 10 minutes, but preferably within 5 minutes at a temperature at or below about 15xc2x0 C.
As used herein, the word xe2x80x9ccomprisingxe2x80x9d is intended to mean including but not necessarily xe2x80x9cconsisting essentially ofxe2x80x9d, xe2x80x9cconsisting ofxe2x80x9d or xe2x80x9ccomposed ofxe2x80x9d. In other words, xe2x80x9ccomprisingxe2x80x9d the listed steps or options need not be exhaustive.
Except in the examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word xe2x80x9cabout.xe2x80x9d All amounts are by weight of the composition, unless otherwise specified.
Evaluation of Cold Brew Product by Qualitative Descriptive Analysis (Q.D.A.)
The color and flavor, including mouthfeel, of iced tea beverages govern their acceptability. A Qualitative Descriptive Analysis (Q.D.A.) test method was selected to systematically characterize and quantify tea beverages based on color, flavor, and mouthfeel. The Q.D.A. method employs a trained panel of expert tasters to quantify the color, flavor and mouthfeel attributes of iced tea beverages relative to defined reference standards.
Expert tasters were chosen by screening prospective panel members for ability to taste standard solutions of acid (citric acid), salt (sodium chloride), sweet (sucrose), and bitter (caffeine) that represent high to low levels (grams per liter) of each flavor attribute as defined in the following table.
Individuals who were able to identify and differentiate the flavor of each test solution at the lowest concentration qualified for participation as an expert taster and were trained to describe and quantify tea beverages using a defined set of attributes to describe color, flavor and mouth feel.
Through a mathematical technique known as Principle Component Analysis four attributes, bitterness (also called bitterness2 or bitter 2 in this application which refers to the bitter aftertaste rather than initial bitterness), smoothness, redness and yellowness were found to be useful for differentiating iced tea beverages. Expert panelists (a minimum of eight) were selected and trained to describe iced tea beverages by rating the intensity of each key attribute (bitterness, smoothness, redness, and yellowness) on a scale of 1-10 by exposing the tasters to extremes of each attribute. For example an infusion of whole leaf Darjeeling tea may be used to define bitterness and yellowness and an infusion of Argentine tea may be used as an example of redness and smoothness. Once trained the expert tasters were tested through blind evaluations of iced tea beverages representing low to high levels of each attribute, provided in random order. Expert tasters evaluated each sample at least 3 times to be assured that panelist ratings were consistent and reproducible. To determine the range of attributes that defines hot brewed iced teas, a variety of teas that represent a broad sampling of the world of teas were evaluated by the trained panel after being prepared by three distinct methods of brewing. All of the water was carbon-filtered tap water. Brewing Method 1 (full flavored brew method) involved the preparation of a concentrate followed by dilution to final beverage strength. Six pitcher or family size tea bags each containing about 7.13 grams of tea leaf were brewed in two quarts of hot freshly boiled water for 30 minutes followed by dilution to beverage strength with an additional two quarts of cold water making.a gallon of beverage. Brewing Method 2 (mild flavored brew method) was a single strength infusion rather than a concentrate preparation. In contrast to Method 1, the tea bags were brewed with the full amount of boiled water (four quarts) for three minutes. Brewing Method 3, designed for the cold brew tea leaf product, was used for the preparation of the inventive product and all reference teas. Six pitcher or family size tea bags were infused in one gallon of cold (60xc2x0 F. or 15xc2x0 C.) carbon filtered water by dunking the bags several times each minute during the 5 minute brewing time.
Product evaluations were conducted in Sensory booths where the trained expert tasters ranked the teas on a 1-10 scale for bitterness, smoothness, redness, and yellowness. The samples were served blind, identified only by a three-digit code and presented in three replications using a balanced block design. Flavor assessment was done under red lights. Appearance was done under white light. The result of this type of test over several different panels, while possibly not being an exact match as to absolute values, will still statistically show the same relative differences between the products.
The teas may be distinguished as those which when cold brewed are poor in color or flavor and are generally lacking in the desirable tea attributes as compared to the teas of the invention having good color and taste and generally attributes that are like those of hot brewed teas. The method for defining the teas is as follows: by plotting each color attribute (red or yellow) vs. a mouthfeel attribute (bitter or smooth), using averaged scores of the panelists, plots are produced which show the inventive teas as superior to other cold brewed teas.
The groupings that result indicate that the world of teas along with the described inventive tea fall in a region of the graphs that is distinct from simply cold brewing all other teas in the data set. The defining region of the group, or Q.D.A. map that relates to the invention, is shown in FIGS. 1, 2, 3 and 4 where teas lying in the region defined by equation 1, 2, 3 and 4, describe the area of applicants"" invention. The teas lying outside of this defined region represent cold brewed teas selected from the world of teas that lack the preferred qualities by comparison. The type of tea, the method of brewing and the data points produced by the Q.D.A. analysis are reported in Table 1 below.
FIGS. 1 through 4 generally represent Q.D.A. maps comparing selected aspects of the tea as measured by the panelists.